Conventional railway car couplings, both freight and passenger, generally consist of two opposed, cooperating, knuckle-like clamps affixed to the ends of the cars. When engaged, the clamps are in intimate relationship with one another. Most designs utilize a vertical, movable locking pin that locks and unlocks the clamps.
In order to uncouple the cars, the locking pin of one clamp is usually raised up a predetermined vertical distance so as to unlock the clamp of the coupling pair. The clamp opens and allows the knuckle to release its hold on the corresponding knuckle, thereby freeing the cars from one another.
Typically, the uncoupling operation is conducted manually. A conductor first engages a lever affixed to the car and the locking pin with a long bar. He then pulls upwardly on the bar moving the lever and thus disengaging the couple.
Manual uncoupling is a dangerous occupation. In crowded and noisy environments, working about and around rolling stock is fraught with risk.
Automatic uncoupling systems have been proposed over the years to reduce the risk of injury and expedite the movement of rail vehicles.
Many of these systems appear to employ dumb, set position hydromechanical devices that cannot accommodate variations in car position. Over a period of time, car placement vis-a-vis the uncoupler may change thereby rendering these systems inoperative. Vigilant efforts must be used to insure that the cars are repeatedly placed exactly in the correct location every time uncoupling is contemplated. Examples include U.S. Pat. Nos. 3,854,598; 3,750,897; 3,682,325; 3,132,749 ; and 1,028,831.
Alternative variations include car mounted decouplers such as U.S. Pat. Nos. 5,139,161; 2,796,615 and 447,578. These apparatus appear to be somewhat complex, probably expensive, and apparently are not suitable for large numbers of standard rail vehicle applications.